[unreadable] [unreadable] Type 1 diabetes mellitus (T1DM) and its complications, especially diabetic nephropathy (DN) represent large public health problems with substantial morbidity and mortality. DN, the leading cause of kidney failure is silent through most of its natural history and DN pathogenesis is incompletely understood. Skin fibroblasts (SF) in vitro behaviors reflect DN risk. Our microarray gene expression data showed highly statistically significantly increased gene expression levels in the mitochondrial (mt) oxidative phosphorolation (OXPHOS) pathway in patients (pts) with rapid vs slow DN development, consistent with increased oxidative stress. Given that gene and protein expression levels may differ, Aim 1 in this proposal will test for mt proteome pathway directional differences in SF of TIDM pts with rapid vs slow DN development using isotope-coded affinity tag and 2-dimensional column chromatography methods and exploratory visual analyses of proteomic data. Our preliminary microarray data also indicated that TIDM pts without DN had highly statistically significantly increased mt pathway expression levels for genes in the OXPHOS, electron transport complexes II, III and IV and tricarboxylic acid (TCA) cycle pathways. Other studies found that non-diabetic first-degree relatives of TIDM pts have evidence of increased oxidative stress. Aim 2 is relevant to the pathogenesis of TIDM per se and will examine mt directional pathway protein expression as outlined above in TIDM (slow DN) pts vs non-diabetic unrelated controls (UC) as well as these UC vs first-degree relatives of TIDM pts. These studies will determine if there is increased mt protein expression in pathways relevant to oxidative stress in uncomplicated TIDM pts and whether this may be genetically determined. These studies could provide surrogate markers of DN and TIDM risk and provide insights into the pathogenesis of TIDM and its renal complications. [unreadable] [unreadable]